Design and fabrication of a polymeric biomems device for sensing FIV P24 antibodies and FeLV P27 antigens in feline saliva

Abstract

Summary form only given. A polymeric BioMEMS device is proposed that performs a qualitative test for Feline immunodeficiency virus (FIV) and Feline leukemia virus (FeLV). FIV and FeLV are both generally termed as retroviruses, which function by inserting their genes into the host's DNA. FIV infected cats range from 1.5-3.0% for healthy, indoor cats and up to 15% for at risk, already diseased cats. FeLV currently infects about 2.0-3.0% of all healthy cats, while as much as 13% of high risk, old, young or ill cats. Current technology for in house testing of both viruses requires blood samples and takes a few minutes to complete the detection. The BioMEMS device proposed here utilizes a non-invasive method and would require a minute or less for a complete result. A successful attempt has been made to integrate the electrochemical deposition technique with a multilayer fabrication approach using various polymers like photodephynable epoxy resin SU8, a conducting polymer polypyrrole (PPy), and a transparent elastomer polydimethylsiloxane (PDMS). The functional unit of the sensor will be fabricated on a silicon wafer. Chromium/Gold micro-electrodes are patterned on silicon wafer and SU-8 has been used for building micro-channels. SU-8 is a negative photoresist with chemical and physical properties suited to this device and is increasingly popular in MEMS devices. Furthermore, PPy will be selectively deposited on gold micro-electrodes and PDMS/protein mixture will be deposited on top of the PPy electrodes. This sensor unit of the wafer will then be diced and employed into a larger, hand held device. FIV antigens and FeLV antibodies will bind onto the selective electrodes (each with their own channel) with an elastomer PDMS. When saliva would pass through the channels, the conjugates would bind on the electrodes and hinder a reduction-oxidation (redox) reaction in a phosphate buffer saline solution. With further testing, resistance levels could be ascertained that would allow simple qualitative measurements for FIV/FeLV testing. The method presented here is innovative because of its ease of fabrication, non-invasive nature and rapid detection system that offer quick results. The non-invasive nature of using saliva offers even at home users a simple method of merely swiping the functional end of the device through the mouth of a cat, washing the electrodes of waste and then submerging in a saline solution. The use of lithographically patterned electrodes and redox reactions allow for a low cost device fabrication that will be able to function with high accuracy and simultaneously introduce a new technique for veterinary antibody/antigen tests